Sonia:
I don't mean to be rude but unless you know what you are doing we can't help you fixing your code every time because you are the only person who knows what you really need. I can send you code to open the serial port and read it but if you need to read the serial port do you know where to stop? at a new line? at a specific number of characters? blocking? nonblocking?
You must understand and code what do you really need. You can use:
-Google
-The Linux Documentation Project
-Language C from K&R
-
http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/pdf/Serial-Programming-HOWTO.pdf
-http://www.easysw.com/~mike/serial/serial.html
In the case of the code you send you are checking the amount of data waiting on the serial port with ioctl, and you code EXPLICITLY
ioctl(fd,FIONREAD, &count);
if(count <= 0) return 0;
And that's why you are getting: "the error is : 0"... as you code.
If you need further guidance you can write me directly to my email and I'll do everything I can.
Cheers,
Alvaro
On 11/18/06, soniathakur3 <> wrote:
hi,
I have a gps module which i am interfacing with the com2 on TS7200.The
code i am using is :
#include <unistd.h>
#include <sys/types.h>
#include <stdio.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <termios.h>
#include <stdlib.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/uio.h>
#include <errno.h>
int open_port(char* device_name)
{
int fd;
fd = open(device_name, O_RDWR | O_NOCTTY| O_NDELAY);
if(fd == -1)
{
printf("Failed to open device \n");
}
return fd;
}
int read_port(int fd)
{
char buffer[512];
int count = 0;
int lines;
while (lines < 80)
{
ioctl(fd,FIONREAD, &count);
if(count <= 0) return 0;
count =read(fd, buffer,512);
printf("the count is: %d\n",count);
lines = lines + 1;
/* Add terminator and print if non-zero */
if(count > 0)
{
buffer[count] = '0\n';
printf("%s\n",buffer);
}
else
{
printf("Zero characters read\n");
}
}
}
void port_configuration(int fd)
{
struct termios options;
fcntl(fd, F_SETFL, FNDELAY);
tcgetattr(fd, &options);
printf("speed in %d out %d\n", options.c_ispeed, options.c_ospeed);
printf("mode in %d out %d\n", options.c_iflag, options.c_oflag);
printf("control flag %d\n", options.c_cflag);
printf("local flag %d\n", options.c_lflag);
options.c_cflag |=(CLOCAL|CREAD);
options.c_cflag &= ~PARENB;
options.c_cflag &= ~CSTOPB;
options.c_cflag |= CS8;
options.c_cflag &= ~CRTSCTS;
cfsetispeed(&options,B4800);
cfsetospeed(&options,B4800);
/* Enable data to be processed */
options.c_lflag &= ~(ICANON | ECHO | ECHOE |ISIG);
options.c_iflag &= ~(IXON | IXOFF | IXANY);
options.c_oflag &= ~ OPOST;
tcsetattr(fd, TCSANOW, &options);
}
int main(int argc, char*argv[])
{
extern int errno;
int fd;
/* check the command */
if(argc < 2)
{
printf("serial_tester<device>\n");
return 0;
}
/* Open the port */
printf("Opening device %s\n", argv[1]);
fd = open_port(argv[1]);
printf("the fd id is : %d\n",fd);
/* Get port configuration */
port_configuration(fd);
/* Set the port to non blocking and read the port */
read_port(fd);
printf("the error is : %d\n",errno);
close((fd));
return 0;
}
and the result that i get is :
$ ./test /dev/ttyAM1
Opening device /dev/ttyAM1
the fd id is : 3
speed in 717120476 out 35296
mode in 256 out 4
control flag 3260
local flag 35360
the error is : 0
could someone help me and tell me what the problem is? I am a novice
and have very less knowledge of linux.
thanks
sonia
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